HR: 0800h
AN: V21A-0390    [Abstracts]
TI: Time Series Radar Observations of a Growing Lava Dome
AU: Wadge, G
EM: gw@mail.nerc-essc.ac.uk
AF: Environmental Systems Science Centre, University of Reading, Reading, RG6 6AL, United Kingdom
AU: Macfarlane, D G
AF: School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
AU: * Odbert, H M
EM: hmo@mail.nerc-essc.ac.uk
AF: Environmental Systems Science Centre, University of Reading, Reading, RG6 6AL, United Kingdom
AU: James, M R
AF: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, United Kingdom
AU: Hole, J K
AF: Environmental Systems Science Centre, University of Reading, Reading, RG6 6AL, United Kingdom
AU: Ryan, G
AF: British Geological Survey/ Montserrat Volcano Observatory, Flemings, Montserrat, W.I., Montserrat
AU: Bass, V
AF: Montserrat Volcano Observatory, Flemings, Montserrat, W.I., Montserrat
AU: De Angelis, S
AF: British Geological Survey/ Montserrat Volcano Observatory, Flemings, Montserrat, W.I., Montserrat
AU: Pinkerton, H
AF: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, United Kingdom
AU: Robertson, D A
AF: School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
AU: Loughlin, S C
AF: British Geological Survey, West Mains Road, Edinburgh, EH9 3LA, United Kingdom
AB: Exogenous growth of Peléean lava domes occurs by addition of lava from a central summit vent and mass wasting on the flanks as rockfalls and pyroclastic flows, forming an apron of talus. We observed this process at the Soufrière Hills Volcano, Montserrat between 30 March and 10 April 2006 using a ground-based imaging mm-wave radar, AVTIS, to measure the shape of the dome surface.From a time series of range and intensity measurements at a distance of six kilometres we measured the topographic evolution of the lava dome. The locus of talus deposition moved to the southeast with time and the talus surface grew upwards on average at about 2 metres per day. The AVTIS measurements show an acceleration in lava extrusion rate on 5 April, with a 2-day lag in the equivalent rockfall seismicity record. We account for the budget of lava addition and dispersal during the eleven days of measurements using: AVTIS range measurements to measure the talus growth (7.2 Mm³, 67%), AVTIS range and intensity measurements to measure the summit lava growth (1.7 Mm³, 16%), and rockfall seismicity and visual observations to measure the pyroclastic flow deposits (1.8 Mm³, 17%). This gives an overall dense rock equivalent extrusion rate of about 9.7 m³s^-1. These figures demonstrate how efficient non-explosive lava dome growth can be in generating large volumes of primary clastic deposits, and how this process could also reduce the propensity for large hazardous pyroclastic flows.
UR: http://www.st- andrews.ac.uk/~mmwave/mmwave/avtis.shtml
DE: 8404 Volcanoclastic deposits
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8429 Lava rheology and morphology
DE: 8485 Remote sensing of volcanoes
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting